While dealing with my nitrite issue I figured I might as well run more tests to get a better idea of everything that is changing in my tank. I figure the more I know about what it normally does the better able to spot something abnormal in the future. Of course most things are likely only spotted by following certain testing frequencies, like my nitrite spike.
I have noted that my GH and KH drop substantially after adding new water.
dGH of 23 to 17 and dKH 21 to 14 in two weeks. But I didn't know how fast that happened, only where they ended up after the two weeks. Now I think there was one more small change in there, so the results are a little higher than they might be unless this is the bottom of the adjustment range and it happens in a one week window.
10 Days later I did a 75% water change followed by a 30% water change the next day. That's most of the water being replaced, about 83% between the two changes.
New readings = 22 dGH and 18 dKH
2 days later
19 dGH and 17 dKH
My pH hovers around 7.8. A little higher than I like but I am not going to try to change it at this point. Not much sense as that is my tap water.
I've no answers for why this happens but it is interesting that it does. I suspect the plants are the culprits.
Yes, plants will take up calcium and magnesium so the GH should lower; some plants can use bicarbonates so that works there too.
In my own situation, with near-zero GH and KH in my tap water, I raise the GH at each water change with Equilibrium. When I began this, I raised it initially to 4 dGH. Over a period of several weeks I worked out the amount of Equilibrium I must add at each 50% water change to maintain the GH around 5 or 6 dGH. I haven't tested post-water change, perhaps I will this morning when I do the water changes in a few moments, to see the variation. But from my calculations based upon how much I add and the GH at the end of the week, I am expecting it to be 2 or 3 degrees.
I was able to partly test this, but will have to continue into the week to get the whole picture. What emerged today was no surprise; the GH in each tank is basically what it has always been when tested just prior to the weekly water change [numbers vary tank to tank, but I keep a written record of all tests back a couple years]. And after a 50% water change in each tank this level was cut in half, which is to be expected with a 50% change using near-zero GH tap water.
Equilibrium was added as usual, and today I was careful to use level tablespoons consistently and I wrote the numbers down so I could more accurately judge the results. It takes a while for the E to completely dissolve, so if I can remember, I will test the GH tomorrow morning and post numbers. A day beyond that might be helpful too, just in case it takes longer for E to dissolve, but I wouldn't think that to be the case.
I did discover that my test kit was not working; I assume it has expired, since I was using it over a year ago (autumn 2011) when I began the Equilibrium, and I had it for a year or more prior to that. Today it was not producing much of any colour, and I remembered I had purchased a new kit a couple months back, so I used that.
I doubt that my GH test kit will last that long at 17 to 23 drops per test.
So, are you going to see if the GH drops after full dissolution of the E and prior to the next water change?
What you are doing, albeit intentionally, is similar to what I am doing by default as I add water at 23dGH to water at 17dGH. To me, smaller more frequent changes would be more beneficial to keep the hardness more stable at a consistently lower level as the plants (assuming still that it is the plants here) are not required to draw quite so much out of the water to bring it down. I am thinking that I might see a lower yet GH if I do that.
Having said that, I wonder if doing so will slow the plant growth... I doubt it as my water is plenty hard.
Yes, the test results will determine if this occurs and to what extent. I doubt it is much, given the small amount of Equilibrium I add. It will be interesting to see what the GH is tomorrow, at its highest which obviously will have to be at or above the level it normally is prior to the water change.
What you are doing, albeit intentionally, is similar to what I am doing by default as I add water at 23dGH to water at 17dGH. To me, smaller more frequent changes would be more beneficial to keep the hardness more stable at a consistently lower level as the plants (assuming still that it is the plants here) are not required to draw quite so much out of the water to bring it down. I am thinking that I might see a lower yet GH if I do that.
Having said that, I wonder if doing so will slow the plant growth... I doubt it as my water is plenty hard.
In my situation, with such a low GH anyway, a difference of 2 or 3 dGH is not going to be an issue for fish, and I have never worried about this. But i agree that it is something you should consider, depending upon the fish species.
The amount of calcium and magnesium taken out by the plants would depend upon the plant species (rate of growth, and whether hardwater or softwater plants to begin with), numbers, and of course having all other nutrients and light sufficient. I don't know to what extent plants can store up calcium, if at all. And both calcium and magnesium if overdosed can cause other nutrient deficiencies, but I've no idea what the specific levels need to be for this to occur.
I selected fish that are good up to 20dGH and 30dGH... so the 20 fish would be my largest concern. I think that keeping the levels around 17 should suffice, but if I can get a bit lower then that will be my aim. Hopefully there will be no more large water changes for a while, or at least I can get a jug of RO water to cut if I know ahead next time.
Now I have the second set of test results. In all tanks, the GH is now exactly 2 dGH higher (with the addition of the Equilibrium) than it was after the water change.
This is not as high as it was prior to the water change, partially explained by my using equal-measure tablespoons this time which has not added as much as I might have done last week when I was much less precise. Also, I did deliberately add less in two tanks.
One needs fairly controlled tests in order to have them practical, so this is fine. It just means I will have to carry this through to next Wednesday's water change in order to have the full picture.
Well that explains why my tank is slowly decreasing gh and kh. Awesome. Tap supply is gh7-8 and kh 1-2. Tank before WC gh 5-6 kh 1. Does prime conditioner affect equilibrium? Asking for my 36g build. So I can get the numbers up a little more
Prime should not affect Equilibrium, since the latter is primarily only the hard minerals (calcium, magnesium, potassium) which are not heavy metals (copper, zinc, iron, etc) and Prime targets heavy metals. Although I don't use Prime, I use another less bothersome conditioner which also detoxifies heavy metals (most, but not all, do) and together there is no issue.
You are the enviable position of having near-perfect tap water, when it comes to GH for plants. Equilibrium is not cheap.
Yeah mate, pretty happy with the water. Matches the plants and fish I intend to use. Just looking at upping the gh and kh by 2-3 points to allow for plant usage. But I'll discuss that when the background is finished
Today being water change day, I tested the GH to complete the experiment. To recap, last week the 50% water change halved the GH in all tanks and adding the Equilibrium resulted in an increase of 2 dGH in all tanks. Prior to today's water change, I tested GH and found in all tanks it is identical to the number last week after the water change. In other words, it is not lowering at all due to the plants assimilation of calcium and magnesium.
Of course, this is with the API test kit which is not high-tech science, but I think the results are probably close enough.
So, even with all my plants, they do not pull sufficient hard mineral from the water such that the GH will lower from week to week.
21st post 75% WC = 21dGH and 16dKH
22nd post 30% WC = 19dGH and 17dKH
25th no WC = 21dGH and 16dKH
26th added 9 catfish, 4 red hygrophila stems , 1/2 a tank surface of duckweed
31st no WC = 21dGH and 16dKH
Difference in the tank since the 26th would be an increase in ammonia concentration, measurable as "non-zero" so not near 0.25ppm except once.
Not a scientific result due to the non-static conditions but interesting that the hardness has not changed since the addition of the new ammonia source. I thought that the 25th result might have been false as I did not do the test myself, my daughter did, perhaps she miss counted as I wouldn't expect the GH to go up while the KH went down. Today's test confirms that the 25th test may have been correct.
Don't think I am going to get anything to explain it so I'll just chalk it up to just one more equilibrium to watch even though I don't know what the other side is.
Oh, here are some pics of the plant growth over the period.
1 = 20th
2 = 28th
3 = 30th
Seems to be a growth spurt in the last few days since the fish have been added.
I did a little more thinking and research on this and realized what may have been going on and why it changed when I added the second batch of fish.
I thought it was the plants using the CaCO3 for the calcium, which it could very well have been but reducing the KH by as much as 25% or more in such a short period seemed a little much... how much calcium can plants take up or more to the point, how much calcium can plants need.... but what do I know?
Seeing as the plants are growing very well, I didn't really need to look too closely at what was really going on. When I added new fish and the plants took off I figured that it was just the added ammonia production, could have been, it certainly was a factor but certainly not the only one.
What I failed to realize is that plants take up a LOT of Carbon... seeing as plants are something like 45% carbon by dry weight it makes sense that they need a lot, and the rate that my plants are growing, they would need far more carbon than calcium.
Initially, with fewer fish (12 barbs), the CO2 generation in the tank was low, relatively. The plants needed carbon so they used the carbon from the low levels of CO2 produced by the fish and the high levels of CaCO3 in the water and reduced the carbonic hardness accordingly. I expect that CO2 is easier for them to use the carbon from so they would probably use it more readily... that is just a guess.
Now, with roughly twice the fish bioload (9 more larger fish) there will be about twice as much CO2 being produced by the fish, of course this is along with the higher ammonia production which helps to balance the system. I have noted that since the 9 additional fish the KH is not lowering as much... barely measurable in fact.
This leads me to believe my guess that the CO2 is used quicker than the CaCO3 and that it was, indeed, my plants directly reducing the KH in the water. Now that there is much more CO2 production, they are just using it first, or faster than CaCO3.
Of course I know that CO2 is often injected into systems to increase plant growth, I knew why but didn't really put it together with my KH adjusting system until now.
That seems logical. Walstad cites some studies on the sources of carbon for aquarium plants. I can't go into all the scientific data in her chapter on this, but there is a list of plants that are effective at using bicarbonates as a source of carbon, and there is a list of those that cannot. Not surprisingly, the users of bicarbonates are many of the stem plants (the fast growers) and of course Vallisneria which is a hard water plant. Those that cannot use bicarbonates are the Echinodorus, Ceratopteris, lily-type, Ludwigia, mosses, to name a few.
Byron.
This is an older thread, you may not receive a response, and could be reviving an old thread. Please consider creating a new thread.
Related Threads
?
?
?
?
?
Tropical Fish Keeping
597.8K posts
83.7K members
Since 2006
forum community dedicated to tropical fish owners and enthusiasts. Come join the discussion about species,breeding, health, behavior, aquariums, adopting, care, classifieds, and more! Open to fish, plants and reptiles living in freshwater or saltwater environments.